1. Field of the Invention
The present invention relates to an optical module for use in optical communication systems, which serve as infrastructure for the Internet or telephone systems.
2. Background Art
In typical conventional optical modules, the outputs of 12 parallel laser diodes are optically coupled together by an optical coupler. In this case, theoretically, the optical power output from the optical coupler is one-twelfth of the optical power input to the coupler. In order to compensate for this power loss, an optical amplifier is integrated into the module (see, e.g., Furukawa Electric Review, No. 121 (March 2008), pages 1-4). However, the use of such an optical amplifier results in an increase in the power consumption of the optical module. Furthermore, the optical amplifier receives and amplifies unwanted return light reflected within the chip and allows it to reenter the laser diodes. As a result, the widths of the spectral lines in the laser diodes vary in a complicated manner with the intensity and the phase of this return light.
To address this problem, improved optical modules have been proposed in which an array or row of laser diodes and a facing optical switch are optically coupled together and the optical switch is used to switch optical paths (see, e.g., Japanese Laid-Open Patent Publication No. H07-154325).